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    <meta property="og:title" content="运算符（Operators）" />
<meta property="og:description" content="中缀运算符（Infix Operators） 中缀运算符需要两个操作数，位于操作数之间。算术和比较运算符是最常见的中缀运算符：
1 &#43; 2 a &lt; b Pony的中缀运算符集和其他语言基本一致。
运算符别名（Operator aliasing） Pony中的大多数中缀运算符都是函数的别名。左边的操作数是调用函数的接收器，右边的操作数作为参数传递。例如，下面的两个表达式是等效的：
x &#43; y x.add(y) &#43;不是只能用于特性类型的特殊符号。任何类型都可以提供自己的add函数，然后可以根据需要对该类型使用&#43;。
在定义自己的add函数时，对参数类型或返回类型没有限制。 &#43;的右侧必须与参数类型匹配，并且&#43;表达式将具有add函数返回的类型。
下面的代码是自定义&#43;运算符的完整示例：
// Define a suitable type class Pair var _x: U32 = 0 var _y: U32 = 0 new create(x: U32, y: U32) =&gt; _x = x _y = y // Define a &#43; function fun add(other: Pair): Pair =&gt; Pair(_x &#43; other._x, _y &#43; other._y) // Now let&#39;s use it class Foo fun foo() =&gt; var x = Pair(1, 2) var y = Pair(3, 4) var z = x &#43; y 使用类型联合体或f界多态性可以在某种程度上重载中缀运算符，但这不在本教程的讨论范围之内。有关更多信息，请参考Pony标准库。" />
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<meta property="article:modified_time" content="2020-04-13T18:18:28+08:00" />
<meta itemprop="name" content="运算符（Operators）">
<meta itemprop="description" content="中缀运算符（Infix Operators） 中缀运算符需要两个操作数，位于操作数之间。算术和比较运算符是最常见的中缀运算符：
1 &#43; 2 a &lt; b Pony的中缀运算符集和其他语言基本一致。
运算符别名（Operator aliasing） Pony中的大多数中缀运算符都是函数的别名。左边的操作数是调用函数的接收器，右边的操作数作为参数传递。例如，下面的两个表达式是等效的：
x &#43; y x.add(y) &#43;不是只能用于特性类型的特殊符号。任何类型都可以提供自己的add函数，然后可以根据需要对该类型使用&#43;。
在定义自己的add函数时，对参数类型或返回类型没有限制。 &#43;的右侧必须与参数类型匹配，并且&#43;表达式将具有add函数返回的类型。
下面的代码是自定义&#43;运算符的完整示例：
// Define a suitable type class Pair var _x: U32 = 0 var _y: U32 = 0 new create(x: U32, y: U32) =&gt; _x = x _y = y // Define a &#43; function fun add(other: Pair): Pair =&gt; Pair(_x &#43; other._x, _y &#43; other._y) // Now let&#39;s use it class Foo fun foo() =&gt; var x = Pair(1, 2) var y = Pair(3, 4) var z = x &#43; y 使用类型联合体或f界多态性可以在某种程度上重载中缀运算符，但这不在本教程的讨论范围之内。有关更多信息，请参考Pony标准库。">
<meta itemprop="dateModified" content="2020-04-13T18:18:28&#43;08:00" />
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<meta name="twitter:title" content="运算符（Operators）"/>
<meta name="twitter:description" content="中缀运算符（Infix Operators） 中缀运算符需要两个操作数，位于操作数之间。算术和比较运算符是最常见的中缀运算符：
1 &#43; 2 a &lt; b Pony的中缀运算符集和其他语言基本一致。
运算符别名（Operator aliasing） Pony中的大多数中缀运算符都是函数的别名。左边的操作数是调用函数的接收器，右边的操作数作为参数传递。例如，下面的两个表达式是等效的：
x &#43; y x.add(y) &#43;不是只能用于特性类型的特殊符号。任何类型都可以提供自己的add函数，然后可以根据需要对该类型使用&#43;。
在定义自己的add函数时，对参数类型或返回类型没有限制。 &#43;的右侧必须与参数类型匹配，并且&#43;表达式将具有add函数返回的类型。
下面的代码是自定义&#43;运算符的完整示例：
// Define a suitable type class Pair var _x: U32 = 0 var _y: U32 = 0 new create(x: U32, y: U32) =&gt; _x = x _y = y // Define a &#43; function fun add(other: Pair): Pair =&gt; Pair(_x &#43; other._x, _y &#43; other._y) // Now let&#39;s use it class Foo fun foo() =&gt; var x = Pair(1, 2) var y = Pair(3, 4) var z = x &#43; y 使用类型联合体或f界多态性可以在某种程度上重载中缀运算符，但这不在本教程的讨论范围之内。有关更多信息，请参考Pony标准库。"/>

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            <a href="/pony-tutorial/reference-capabilities/combining-capabilities.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              权能合并（Combining Capabilities）
            </a>
          </li>
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            <a href="/pony-tutorial/reference-capabilities/arrow-types.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              箭头的用法（Arrow Types aka Viewpoints）
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          <li class="f6 fw4">
            <a href="/pony-tutorial/reference-capabilities/capability-matrix.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              权能矩阵（Reference Capability Matrix）
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          </li>
        </ul>
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              概述（Overview）
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          <li class="f6 fw4">
            <a href="/pony-tutorial/object-capabilities/object-capabilities.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              对象权能模型（Object Capabilities）
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            <a href="/pony-tutorial/object-capabilities/trust-boundary.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              边界信任（Trust Boundary）
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          </li>
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              概述（Overview）
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          <li class="f6 fw4">
            <a href="/pony-tutorial/pattern-matching/match.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              匹配表达式（Match Expressions）
            </a>
          </li>
          <li class="f6 fw4">
            <a href="/pony-tutorial/pattern-matching/as.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              as操作符（As Operator）
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          </li>
        </ul>
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      <li class="f5 w-100 hover-bg-light-gray hover-accent-color-light fw8">
        <a href="javascript:void(0)" class="js-toggle dib w-100 link mid-gray hover-accent-color-light pl2 pr2 pv2 " data-target=".generics">泛型（Generics）</a>
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          <li class="f6 fw4">
            <a href="/pony-tutorial/generics.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              概述（Overview）
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          </li>
          <li class="f6 fw4">
            <a href="/pony-tutorial/generics/generics-and-reference-capabilities.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              泛型和引用权能（Generics and Reference Capabilities）
            </a>
          </li>
          <li class="f6 fw4">
            <a href="/pony-tutorial/generics/generic-constraints.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              泛型约束（Constraints）
            </a>
          </li>
        </ul>
      </li>
      
      <li class="f5 w-100 hover-bg-light-gray hover-accent-color-light fw8">
        <a href="javascript:void(0)" class="js-toggle dib w-100 link mid-gray hover-accent-color-light pl2 pr2 pv2 " data-target=".packages">包（Packages）</a>
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              概述（Overview）
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              包机制（Package System）
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            <a href="/pony-tutorial/packages/use-statement.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              包的使用方式（Use Statement）
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            <a href="/pony-tutorial/packages/standard-library.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              标准库（Standard Library）
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              概述（Overview）
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            <a href="/pony-tutorial/testing/ponytest.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Testing with Ponytest
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        <a href="javascript:void(0)" class="js-toggle dib w-100 link mid-gray hover-accent-color-light pl2 pr2 pv2 " data-target=".c-ffi">C FFI</a>
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          <li class="f6 fw4">
            <a href="/pony-tutorial/c-ffi.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              概述（Overview）
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          <li class="f6 fw4">
            <a href="/pony-tutorial/c-ffi/calling-c.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Calling C from Pony
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          <li class="f6 fw4">
            <a href="/pony-tutorial/c-ffi/linking-c.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Linking to C Libraries
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          <li class="f6 fw4">
            <a href="/pony-tutorial/c-ffi/c-abi.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              C ABI
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            <a href="/pony-tutorial/c-ffi/callbacks.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Callbacks
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          <li class="f6 fw4">
            <a href="/pony-tutorial/gotchas.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              概述（Overview）
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          <li class="f6 fw4">
            <a href="/pony-tutorial/gotchas/divide-by-zero.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Divide by Zero
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          <li class="f6 fw4">
            <a href="/pony-tutorial/gotchas/garbage-collection.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Garbage Collection
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              Scheduling
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              Function Call Side Effects
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            <a href="/pony-tutorial/gotchas/recursion.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Recursion
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        <a href="javascript:void(0)" class="js-toggle dib w-100 link mid-gray hover-accent-color-light pl2 pr2 pv2 " data-target=".appendices">附录（Appendices）</a>
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              Lexicon
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            <a href="/pony-tutorial/appendices/symbol-lookup-cheatsheet.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Symbol Lookup Cheatsheet
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            <a href="/pony-tutorial/appendices/keywords.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Keywords
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              Examples
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              Compiler Arguments
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              Memory Allocation at Runtime
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            <a href="/pony-tutorial/appendices/garbage-collection.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Garbage Collection with Pony-ORCA
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            <a href="/pony-tutorial/appendices/platform-dependent-code.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Platform-dependent code
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            <a href="/pony-tutorial/appendices/error-messages.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              A Short Guide to Pony Error Messages
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              Program Annotations
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            <a href="/pony-tutorial/appendices/serialisation.html" class="db link hover-bg-gray hover-white pl3 pr2 pv2 black ">
              Serialisation
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    <p class="f5 b mb3">What's in this document</p>
      <nav id="TableOfContents">
  <ul>
    <li><a href="#中缀运算符infix-operators">中缀运算符（Infix Operators）</a></li>
    <li><a href="#运算符别名operator-aliasing">运算符别名（Operator aliasing）</a></li>
    <li><a href="#短路求值short-circuiting">短路求值（Short circuiting）</a></li>
    <li><a href="#一元运算符unary-operators">一元运算符（Unary operators）</a></li>
    <li><a href="#运算符优先级precedence">运算符优先级（Precedence）</a></li>
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</div><div class="order-1 w-60-l mw9 ph0 ph5-ns mid-gray nested-copy-line-height no-underline nested-links nested-img nested-copy-seperator nested-blockquote mt0-ns" style="flex-grow:1;">
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          <a id="doc-menu-toggle" class="icon icon-menu" href="javascript:void(0)" onClick="hideShowDM()"></a><a id="context-menu-toggle" class="icon icon-menu" href="javascript:void(0)" onClick="hideShowCM()"></a></div>

        <div class="documentation-copy center mw7" id="content">
          <header class="mt4 w-100">
            <p class="f6 b helvetica tracked">
                
              表达式（EXPRESSIONS）
            </p>
            <h1 class="f1 athelas mb1">运算符（Operators）</h1>
          </header>

          <main class="nested-copy-line-height lh-copy serif f4 nested-links nested-img mid-gray pr4-l"><!-- raw HTML omitted -->
<h2 id="中缀运算符infix-operators">中缀运算符（Infix Operators）</h2>
<!-- raw HTML omitted -->
<p>中缀运算符需要两个操作数，位于操作数之间。算术和比较运算符是最常见的中缀运算符：</p>
<pre><code class="language-pony" data-lang="pony">1 + 2
a &lt; b
</code></pre><!-- raw HTML omitted -->
<p>Pony的中缀运算符集和其他语言基本一致。</p>
<!-- raw HTML omitted -->
<h2 id="运算符别名operator-aliasing">运算符别名（Operator aliasing）</h2>
<!-- raw HTML omitted -->
<p>Pony中的大多数中缀运算符都是函数的别名。左边的操作数是调用函数的接收器，右边的操作数作为参数传递。例如，下面的两个表达式是等效的：</p>
<pre><code class="language-pony" data-lang="pony">x + y
x.add(y)
</code></pre><!-- raw HTML omitted -->
<p><code>+</code>不是只能用于特性类型的特殊符号。任何类型都可以提供自己的<code>add</code>函数，然后可以根据需要对该类型使用<code>+</code>。</p>
<!-- raw HTML omitted -->
<p>在定义自己的<code>add</code>函数时，对参数类型或返回类型没有限制。 <code>+</code>的右侧必须与参数类型匹配，并且<code>+</code>表达式将具有<code>add</code>函数返回的类型。</p>
<!-- raw HTML omitted -->
<p>下面的代码是自定义<code>+</code>运算符的完整示例：</p>
<pre><code class="language-pony" data-lang="pony">// Define a suitable type
class Pair
  var _x: U32 = 0
  var _y: U32 = 0

  new create(x: U32, y: U32) =&gt;
    _x = x
    _y = y

  // Define a + function
  fun add(other: Pair): Pair =&gt;
    Pair(_x + other._x, _y + other._y)

// Now let's use it
class Foo
  fun foo() =&gt;
    var x = Pair(1, 2)
    var y = Pair(3, 4)
    var z = x + y
</code></pre><!-- raw HTML omitted -->
<p>使用类型联合体或f界多态性可以在某种程度上重载中缀运算符，但这不在本教程的讨论范围之内。有关更多信息，请参考<a href="https://stdlib.ponylang.org">Pony标准库</a>。</p>
<!-- raw HTML omitted -->
<p>如果您不想，则不必担心任何这些。您可以像使用任何其他语言一样简单地将现有的中缀运算符用于数字，而不必为您自己的类型提供它们。</p>
<!-- raw HTML omitted -->
<p>中缀运算符函数别名的完整列表：</p>
<hr>
<!-- raw HTML omitted -->
<table>
<thead>
<tr>
<th>运算符</th>
<th>函数</th>
<th>描述</th>
<th>注意</th>
</tr>
</thead>
<tbody>
<tr>
<td><code>+</code></td>
<td>add()</td>
<td>Addition</td>
<td></td>
</tr>
<tr>
<td><code>-</code></td>
<td>sub()</td>
<td>Subtraction</td>
<td></td>
</tr>
<tr>
<td><code>*</code></td>
<td>mul()</td>
<td>Multiplication</td>
<td></td>
</tr>
<tr>
<td><code>/</code></td>
<td>div()</td>
<td>Division</td>
<td></td>
</tr>
<tr>
<td><code>%</code></td>
<td>rem()</td>
<td>Remainder</td>
<td></td>
</tr>
<tr>
<td><code>%%</code></td>
<td>mod()</td>
<td>Modulo</td>
<td>Starting with version <code>0.26.1</code></td>
</tr>
<tr>
<td><code>&lt;&lt;</code></td>
<td>shl()</td>
<td>Left bit shift</td>
<td></td>
</tr>
<tr>
<td><code>&gt;&gt;</code></td>
<td>shr()</td>
<td>Right bit shift</td>
<td></td>
</tr>
<tr>
<td><code>and</code></td>
<td>op_and()</td>
<td>And, both bitwise and logical</td>
<td></td>
</tr>
<tr>
<td><code>or</code></td>
<td>op_or()</td>
<td>Or, both bitwise and logical</td>
<td></td>
</tr>
<tr>
<td><code>xor</code></td>
<td>op_xor()</td>
<td>Xor, both bitwise and logical</td>
<td></td>
</tr>
<tr>
<td><code>==</code></td>
<td>eq()</td>
<td>Equality</td>
<td></td>
</tr>
<tr>
<td><code>!=</code></td>
<td>ne()</td>
<td>Non-equality</td>
<td></td>
</tr>
<tr>
<td><code>&lt;</code></td>
<td>lt()</td>
<td>Less than</td>
<td></td>
</tr>
<tr>
<td><code>&lt;=</code></td>
<td>le()</td>
<td>Less than or equal</td>
<td></td>
</tr>
<tr>
<td><code>&gt;=</code></td>
<td>ge()</td>
<td>Greater than or equal</td>
<td></td>
</tr>
<tr>
<td><code>&gt;</code></td>
<td>gt()</td>
<td>Greater than</td>
<td></td>
</tr>
<tr>
<td><code>&gt;~</code></td>
<td>gt_unsafe()</td>
<td>Unsafe greater than</td>
<td></td>
</tr>
<tr>
<td><code>+~</code></td>
<td>add_unsafe()</td>
<td>Unsafe Addition</td>
<td></td>
</tr>
<tr>
<td><code>-~</code></td>
<td>sub_unsafe()</td>
<td>Unsafe Subtraction</td>
<td></td>
</tr>
<tr>
<td><code>*~</code></td>
<td>mul_unsafe()</td>
<td>Unsafe Multiplication</td>
<td></td>
</tr>
<tr>
<td><code>/~</code></td>
<td>div_unsafe()</td>
<td>Unsafe Division</td>
<td></td>
</tr>
<tr>
<td><code>%~</code></td>
<td>rem_unsafe()</td>
<td>Unsafe Remainder</td>
<td></td>
</tr>
<tr>
<td><code>%%~</code></td>
<td>mod_unsafe()</td>
<td>Unsafe Modulo</td>
<td>Starting with version <code>0.26.1</code></td>
</tr>
<tr>
<td><code>&lt;&lt;~</code></td>
<td>shl_unsafe()</td>
<td>Unsafe left bit shift</td>
<td></td>
</tr>
<tr>
<td><code>&gt;&gt;~</code></td>
<td>shr_unsafe()</td>
<td>Unsafe right bit shift</td>
<td></td>
</tr>
<tr>
<td><code>==~</code></td>
<td>eq_unsafe()</td>
<td>Unsafe equality</td>
<td></td>
</tr>
<tr>
<td><code>!=~</code></td>
<td>ne_unsafe()</td>
<td>Unsafe non-equality</td>
<td></td>
</tr>
<tr>
<td><code>&lt;~</code></td>
<td>lt_unsafe()</td>
<td>Unsafe less than</td>
<td></td>
</tr>
<tr>
<td><code>&lt;=~</code></td>
<td>le_unsafe()</td>
<td>Unsafe less than or equal</td>
<td></td>
</tr>
<tr>
<td><code>&gt;=~</code></td>
<td>ge_unsafe()</td>
<td>Unsafe greater than or equal</td>
<td></td>
</tr>
<tr>
<td><code>+?</code></td>
<td>add_partial()?</td>
<td>Partial Addition</td>
<td></td>
</tr>
<tr>
<td><code>-?</code></td>
<td>sub_partial()?</td>
<td>Partial Subtraction</td>
<td></td>
</tr>
<tr>
<td><code>*?</code></td>
<td>mul_partial()?</td>
<td>Partial Multiplication</td>
<td></td>
</tr>
<tr>
<td><code>/?</code></td>
<td>div_partial()?</td>
<td>Partial Division</td>
<td></td>
</tr>
<tr>
<td><code>%?</code></td>
<td>rem_partial()?</td>
<td>Partial Remainder</td>
<td></td>
</tr>
<tr>
<td><code>%%?</code></td>
<td>mod_partial()?</td>
<td>Partial Modulo</td>
<td>Starting with version <code>0.26.1</code></td>
</tr>
</tbody>
</table>
<hr>
<!-- raw HTML omitted -->
<h2 id="短路求值short-circuiting">短路求值（Short circuiting）</h2>
<!-- raw HTML omitted -->
<p>与Bool变量一起使用时，and和or运算符会采用使用 <strong>短路求值（short circuiting）</strong> 。第一个操作数始终会被求值，第二个操作数仅在对有影响结果时，才会被求值。</p>
<!-- raw HTML omitted -->
<p>对于<code>and</code>，如果第一个操作数是 <strong>false</strong> ，则不会对第二个操作数求值，因为它不会影响结果。</p>
<!-- raw HTML omitted -->
<p>对于<code>or</code>，如果第一个操作数是 <strong>true</strong> ，则不会对第二个操作数求值，因为它不会影响结果。</p>
<!-- raw HTML omitted -->
<p>这是编译器内置的特殊功能，不能与其他类型的运算符别名一起使用。</p>
<!-- raw HTML omitted -->
<h2 id="一元运算符unary-operators">一元运算符（Unary operators）</h2>
<!-- raw HTML omitted -->
<p>一元运算符的与中缀运算符的别名机制类似，但只有一个操作数。例如，以下表达式是等效的：</p>
<pre><code class="language-pony" data-lang="pony">-x
x.neg()
</code></pre><!-- raw HTML omitted -->
<p>一元运算符函数别名的完整列表：</p>
<hr>
<!-- raw HTML omitted -->
<table>
<thead>
<tr>
<th>运算符</th>
<th>函数</th>
<th>描述</th>
</tr>
</thead>
</table>
<ul>
<li>
<pre><code>   | neg()        | Arithmetic negation
</code></pre>
</li>
</ul>
<p>not      | op_not()     | Not, both bitwise and logical
-~       | neg_unsafe() | Unsafe arithmetic negation</p>
<hr>
<!-- raw HTML omitted -->
<h2 id="运算符优先级precedence">运算符优先级（Precedence）</h2>
<!-- raw HTML omitted -->
<p>在Pony中，一元运算符的优先级总是比中缀运算符高：<code>not a == b</code>将被解释为<code>（not a）== b</code>而不是<code>not（a == b）</code>。</p>
<!-- raw HTML omitted -->
<p>在复杂表达式中使用中缀运算符时， <strong>优先级</strong> 问题很关键。试着评估下面这句表达式的运算符优先级：</p>
<pre><code class="language-pony" data-lang="pony">1 + 2 * 3  // Compilation failed.
</code></pre><!-- raw HTML omitted -->
<p>如果我们计算加法，得到的结果为9，如果计算乘法，得到的结果为7。在数学中有一套评估运算符优先级的规则，大多数编程语言都遵循这种方法。</p>
<!-- raw HTML omitted -->
<p>这样做的问题是程序员必须记住规则，通常人们对这样的事情不是很擅长。大多数人会记得在加法之前要进行乘法运算，但是左移与按位运算又如何呢？有时人们会忘记（或猜错），这会导致错误。更糟糕的是，这些错误通常很难发现。</p>
<!-- raw HTML omitted -->
<p>Pony采取了不同的做法，去避免这个问题。 如果一个表达式中需要使用多个中缀运算符 <strong>必须</strong> 使用括号来消除歧义。如果您不这样做，编译时会报错。</p>
<!-- raw HTML omitted -->
<p>上面的示例在Pony中是非法的，正确的写法为：</p>
<pre><code class="language-pony" data-lang="pony">1 + (2 * 3)  // 7
</code></pre><!-- raw HTML omitted -->
<p>如果使用的是相同的运算符就可以省略括号：</p>
<pre><code class="language-pony" data-lang="pony">1 + 2 + 3  // 6
</code></pre><!-- raw HTML omitted -->
<p>同时，一元运算符和中缀运算符的混合不需要额外的括号，因为一元运算符总是和操作数紧贴在一起，因此如果上面的示例使用的是负3是没问题的。但是如果用到不同的中缀运算符：</p>
<pre><code class="language-pony" data-lang="pony">1 + 2 * -3  // Compilation failed.
</code></pre><!-- raw HTML omitted -->
<p>仍然需要括号来消除歧义，就像上面所做的一样，但是不需要负数一元运算（<code>-</code>）加括号：</p>
<pre><code class="language-pony" data-lang="pony">1 + (2 * -3)  // -5
</code></pre><!-- raw HTML omitted -->
<p>我们可以看到，将一元运算符应用在中缀运算之前更有意义，因为它仅作用于表达式中的单个数字，因此它永远不会模棱两可。</p>
<!-- raw HTML omitted -->
<p>一元运算符也可以应用于括号，在括号之外，所有中缀运算符之前，对括号中的运算结果进行操作：</p>
<pre><code class="language-pony" data-lang="pony">1 + -(2 * -3)  // 7
</code></pre></main>
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